Development of Residual Gas X-ray BPM for PETRA III€¦ · P. Ilinski, DESY/HASYLAB XBPM workshop NSLS II, 25.02.09 White undulator beam X-ray BPM Type Beam halo Blade BPMs Center

P. Ilinski, DESY/HASYLAB XFEL-WPG3 meeting, 17.06.08

Development of Residual Gas X-ray

BPM for PETRA III

Petr Ilinski

DESY/HASYLAB

P. Ilinski, DESY/HASYLAB XBPM workshop NSLS II, 25.02.09

White undulator beam X-ray BPM

� Type� Beam halo

� Blade BPMs

� Center of gravity of the beam

� Residual Gas BPMs

� Diamond BPMs

� will not work for PETRA III


Blades BPMAPS X-ray BPM


Background Radiation


APS solution - Decker Distortion

Allowed to incorporate XBPMs into APS global orbit feedback


ELETRA solution - Electron Energy Analyzer

A. Galimberti, et al. NIM A 467 (2001) 221


PETRA III

E = 6 GeV, Imax = 100 mA 8 new straight sections

�� 1.0 nmrad, � = 1% 13 ID beamlines

Lu � 2 m, 5m, 20 m 2009 - Start of user operation

PETRA III


Residual Gas X-ray BPM

� Function� Provide direct, non-destructive measurements of

center of gravity of the beam

� Necessity / Feasibility� Windowless beamlines

� Differential pumping

� Spatial resolution� Less then 10 um

� Reliability� No beam heated components

� MCP degradation


Residual Gas X-ray BPMGeneral layout

MCPPLCCD

P O I M E R

Ion trajectories

E

MCP


Spatial Resolution

� Signal / Noise

� Residual gas cross sections

� Scattering background

� Quality of the electrical field

� Nonuniformity of the electrical field

� Transverse component of the electrical field

� Initial kinetic energy of Ions/Electrons

� Thermal motion

� Momentum transfer during the ionization

� Readout resolution

� MCP/Optics/CCD

� Electronics readout

� Data processing

� Sub-pixel resolution


Signal levels


Signal spatial distributionTotal power

PETRA III undulator 2.9 cm, 2m, K=0.6, Power @ 20 m, 10x10 mm2


Signal level

PETRA III undulator 2.9 cm, 2m, K=0.6, 100 mA


Signal spatial distributionMono beam

PETRA III undulator 2.9 cm, 2m, K=0.6, Flux @ 20 m, 20x20 mm2

1 keV 5 keV


PETRA III Generic Beamline

RGXBPMs


Design considerations

� Collimation / shielding

� Electrical field quality

� Ionization Cross section

� choice of gas - N2

� residual gas pressure ~ 10-6 mbar

� Reliability

� MCP degradation

� Readout

� Optical readout

� + Beam Profile

� resolution vs. FOV

� slow

� Split electrode

� Center of gravity

� fast, reliable, long electrodes & MCP

� 1D strip detector (PSI)

� very fast, no MCP


PETRA III RGXBPMCanted undulators beamline

Constrain - limited space


Electrostatic/Ion beam propagation ModelingCST PARTICLE STUDIO


Electrostatic ModelingCST PARTICLE STUDIO

Center Edge


Ion Beam Propagation


RGXBPM for PETRA IIIPrototype #3


RGXBPM for PETRA IIIFinal version


Tests of RGXBPM

� Test requirements (needs dedicated beamline !)� White undulator beam

� No windows

� Adequate scattering background

� Radiation environment (inside the SR)

� A number of RGXBPM prototypes were tested� Test stand, e-gun

� DESY BW3

� ESRF ID30, ID6


Test Setup ESRF ID06 03/08, “white” undulator beam, controlled gas environment


Beam ProfilesRGXBPM, 3rd prototype, Optical Readout

ESRF ID06, 300 μm diamond window, undulator u18, gap 9 mm, E1 = 16.7 keV

Exposure time = 500 ms, Optical resolution = 15 μm/pixel

MCPwindow


ResolutionRGXBPM 3rd prototype, Optical readout

ESRF 05/2008, ID6, 300 μm diamond, I = 80 mA, u18 gap = 9 mm, E1 = 16.7 keV,

N2=4*10-6 mbar, RGXBPM vertical scan, step =10 um

10 um


ResolutionRGXBPM 3rd prototype, Electrical readout

ESRF 07/2008, ID6, 300 μm diamond, I = 80 mA, u18 gap=8,10,12 mm

N2=4*10-6 mbar, RGXBPM vertical scan

(S1-S2)/(S1+S2)

S1, S2


ResolutionRGXBPM 3rd prototype, Electrical readout

ESRF 07/2008, ID6, 300 μm diamond, I = 80 mA, u18 gap=8 mm

RGXBPM vertical scan, step = 20 um

(S1-S2)/(S1+S2)

S1

S2

20 um


ResolutionRGXBPM 3rd prototype, Optical readout

e-bmpV

rgxbpmV

30 um

ESRF ID06 03/08, e-beam refill, u18 gap=9 mm, E1=16.7 keV300 μm diamond window, N2 = 2.5e-6 mbar


PETRA III OperationSpatial distribution of undulator radiation, E=1 keV @ 20 m, u29, K=1.2

Electrical readout, MCP

Electrode

Electrode

ESRFmask

� 15-mm-diam absorber apperture is located at 16m

� side electrodes are to detect soft x-ray beam component

Documents

Development of Residual Gas X-ray BPM for PETRA III€¦ · P. Ilinski, DESY/HASYLAB XBPM workshop NSLS II, 25.02.09 White undulator beam X-ray BPM Type Beam halo Blade BPMs Center